EEVEE Edge detect effect
As cubes (head), or scaled cubes (arms, notice the variations of the edge thickness for arms), you can compare the location to some threshold.
Edge detection: top line in the image below
We can take generated coordinates, and recenter them to -0.5/+0.5,
Get absolute of that.
Compare each coordinate to a threshold.
And detect the edge if more than two dimensions are above this threshold.
Camera facing effect: bottom line below
Compare the incoming vector to the normal using a dot product.
Keep only what is above a threshold.
Combine with the edge detection.